In thermally assisted optical/magnetic data storage, information bits are recorded on a layer of a storage medium at elevated temperatures, and the heated area in the storage medium determines the data bit dimension. Heat assisted magnetic recording (HAMR) generally refers to the concept of locally heating a recording medium to reduce the coercivity so that an applied magnetic writing field can more easily direct the magnetization of the recording medium during the temporary magnetic softening caused by the heat source. The coercivity of the medium at ambient temperature can be much higher than the coercivity during recording, thereby enabling stability of the recorded bits at higher storage densities and with smaller bit cells. Heat assisted magnetic recording can be applied to any type of magnetic storage media, including longitudinal media, perpendicular media and patterned media.
Heat assisted magnetic recording has been proposed for extending the areal storage density of magnetic disk drives to 1 Tb/in2 or higher. One of the enablers for this technology is an optical transducer (OT) which is capable of efficiently delivering light energy to the recording medium in a spot confined approximately to the dimensions of the magnetic mark to be recorded, i.e., at dimensions well below the diffraction limit around the visible region of the electromagnetic spectrum. The light energy heats up the magnetic recording medium, which lowers its coercivity. Magnetic switching of the bit in the media can then be achieved by applying a magnetic field in the desired direction. To produce this magnetic field it is necessary to integrate metallic and/or magnetic structures into the recording head and to place them in close proximity to the optical transducer. The combination of a conventional “pole” based magnetic recording head structure and an optical transducer results in a complex structure. In addition, every metallic structure close to the optical transducer negatively influences its optical performance. It is therefore desirable to keep the number and size of the metallic structures near the optical transducer to a minimum.
Furthermore, if a thin film optical waveguide is used to deliver the optical power to the transducer, metallic structures inside this waveguide would also hinder the light from freely propagating, and further diminish the optical energy density at the optical transducer.
Magnetic write heads have been proposed wherein the magnetic write field is produced by, and/or amplified by, a wire positioned adjacent to a write pole at an air bearing surface (ABS) of the head. The wire can generate large local magnetic fields by way of large current densities in the wire. This recording head is referred to as a wire amplified magnetic recording (WAMR) head. The flux density from the wire can be high enough to affect the magnetization of an adjacent storage disc, or to magnetize a write pole and generate additional flux density with an appropriate field direction and spatial profile to augment the write field.
It would be desirable to combine the WAMR magnetic field delivery concept with the optical requirements of a HAMR head.